High solids ethylene acrylic acid aqueous dispersions and methods of producing same

ABSTRACT

A uniquely treated bead of ethylene acrylic acid (EAA) capable of forming a high solids aqueous dispersion in excess of 38% solids wherein the EAA may be prepared by either batch or continuous processes wherein the EAA is substantially fully reacted with ammonia, sodium or potassium in little or substantial absence of water, followed by a separate aqueous dispersion step, resulting in a unique and quick-drying dispersion material highly useful in coating, adhesive, laminating, ink and similar processes, and wherein operating expense and environmental concerns are at a minimum as a consequence thereof. 
     The treated EAA may be prepared in a substantially dry to merely moist state for incorporation into an aqueous dispersion with high percentages of EAA having either higher or lower molecular weight with low viscosities as compared to heretofore.

Cross-Reference to Related Application

This application is a continuation of application Ser. No. 07/795,869,now abandoned filed Nov. 20, 1990 which is a a continuation-in-part ofthe prior application to Ferrell et al U.S. Ser. No. 07/702,095, filedMay 20. 1991 now abandoned.

BACKGROUND OF THE INVENTION

Ethylene acrylic acid (EAA) is a ubiquitous substance with wide-ranginguses in industry and commerce. Among these multiferous uses is itsincorporation into an aqueous dispersion after batch reaction fordiverse coating and like purposes, as are well known in the art.

Aqueous dispersions have significant advantages when used in the coatingarts as compared to the common use of organic solvent dispersions andsolutions, especially with respect to environmental, fire/explosivehazards, and pollution factors of organic volatiles and the significantdifficulty and cost of collecting and satisfactorily handling the sameduring application and curing of the coatings.

On the other hand, as noted further hereinafter, aqueous-based EAAcoating materials, as heretofore available, have relatively high watercontent, which while explosive-safe and fume safe, require excessive andoften unacceptable drying times, whereby in weighing the practical andeconomic merits of one against the other, the environmentallyundesirable organic-based coatings have necessarily remained inwidespread usage despite the increasing inveighment thereagainst.

Such prior art teachings as to high mole ratio EAA dispersions areillustrated by the Dow Chemical patent to McCann et al U.S. Pat. No.3,799,901, the teachings of which are incorporated herein by reference.With respect to the Dow patent teachings as well as to present andindeed heretofore long-term availability of EAA aqueous dispersions,such dispersions are readily commercially available at 35% and 25% EAAsolids proportion. The starting EAA bead resin therefor is availablefrom various suppliers, including Dow Chemical Company under thetrademark "Primacor" adhesive polymer utilizing beads identified as"5980"or "5990". Such beads are available in ammonia dispersions, asthose known as "ADCOTE" of Morton Thiokol Chemical Corporation, with 25%EAA solids proportion using Dow Chemical "5980" beads (high molecularweight) or with 35% EAA solids using Dow "5990" beads (low molecularweight). In like manner, "YUKALON" EAA resin is available fromMitsubishi Chemical Corporation and is comparable to the Dow "5980"resin, while Dow Chemical itself has marketed "Primacor 4983 dispersionusing the higher molecular weight "5980" beads, and "Primacor 4990"dispersion using the lower molecular weight "5990" beads. Theavailability and properties of these products are well known.

When 5980-type beads are provided in such a 25% solids dispersion fromthese varied commercial sources, the EAA solids are of a size on theorder of 500Å and the dispersion is water white in appearance, forexample. Such resin as noted prior to incorporation into the dispersionis of relatively high molecular weight and melts at higher temperature.

It is evident that such 25% dispersions with such a high water contentpresent significant problems in coating and other applications withrespect to reasonably efficient and rapid drying thereof, with severedemands of both time and heat input in an effort to accelerate dryingwithout damage to the substrate in any way.

As noted, a somewhat higher 35% solids proportion is available, wherein,however, the viscosity is substantially higher with resultant greaterdifficulty in effecting ready coatings therewith. The 35% dispersion of5990-type beads further is of lower molecular weight and with a lowermelting point as compared to the 25% 5980-type dispersion, therebyhandicapping the application of high-heat drying even if the applicationof the coating is successful. Such known materials, whether "25% " or"35% " in fact can not and do not feasibly serve as replacements for theunwanted organic EAA coatings, despite repeated efforts to utilize thesame. It is important to note that a commercially usable 35% solids5980-type dispersion cannot heretofore be successfully produced.

Efforts to effect suitable dispersions of this type are taught in theaforesaid U.S. Pat. No. 3,799,901 of Dow Chemical Corporation, forexample. It will be noted that while following the processes taught inthat patent, it is stated that polymer solids as high as "40% " or "50%" may be employed. However, the resultant dispersions at these highsolids levels are useless and totally unsuitable for any coatingapplications. Indeed, the same are described in that patent as "viscouspaste" or "very viscous latex", and obviously cannot be employed forpaper or other running length substrate coating.

Prior to the present invention, for usable coating purposes and toachieve a serviceable low viscosity, the EAA solids concentration ofnecessity had to be lowered to about 25% or less, as with the aforesaid5980-type beads, with resultant increase in water or liquid andunworkable heat requirements and drying times. Such also occurs withdilutions of the high solids "pastes" of the above-noted patent-taughtprocesses.

Accordingly, at the present time, EAA treated by known ordinaryprocedures for running coating operations, for example, is availableonly the order of 25% in aqueous dispersions. The techniques for doingso at the present time even to achieve this ratio are not efficient andindeed little more than individual batch processes incapable or quick orready variation thereof as for incorporation of added constituents thatmay be desirable.

Further, briefly stated, and with reference to the Dow patent, forexample, the known batch techniques of producing even the presentlyavailable 25% and 35% dispersions are slow and inefficient as a resultof excess quantities of water in bead preparation. Thus, illustratively,EAA beads are placed in a reactor with addition of water and substantialquantities of ammonia (i.e. 0.70 mole ratio ammonium hydroxide) toslowly react, resulting in an initital relatively highly viscous andrelatively low EAA concentration aqueous dispersion. The reactor stepsmay be repeated as desired. Further, such reactor production thereofdoes not readily permit the controlled introduction of desired additiveswhich are helpful in diverse coating formulations.

While the exact nature of the reaction achieved by the present inventionas discussed hereinafter is not precisely known, it is believed that thesubstantially different and markedly improved results are brought aboutby the introduction of substantially lower effective amounts of theammonia directly to the EAA molecules in the significant absence ofwater. In this manner the ammonia targets reactor sites on the moleculein a manner that the prior art technique is incapable of achieving.

The literature shows that ammonium hydroxide (NH₄ OH), may be used totreat a carboxylic acid, resulting in an ammonium salt. In such priorart treatments, high EAA concentrations, approaching 35% solids and offlowable character, are unknown. Reference is made to a publication ofDow Chemical Company entitled "Separation of Ionomer Dispersions" fromwhich it is clear that the use of high mole ratio hydroxides result innon-pourable gels and undigested EAA whenever high solids are sought,which materials are undesirable and all but useless.

Brief Summary of the Invention

The present invention relates to the unique formulation of lowviscosity, quickly driable and readily usable high solids EAA aqueousdispersions of 38% solids or higher, as well as also the efficientproduction of such ethylene acrylic acid aqueous dispersions having asignificantly high solids-to-water ratio, by special treatment of theEAA prior to dispersion preparation, which achieves unique and highlydesirable results.

The present invention, inter alia, in unique and novel manner, advancesthe teachings of the aforementioned Dow patent in major and significantrespects. That is to say, in following the processes of that patent forhigh EAA solids contents, a virtually solid block of material results.It is a chief purpose of this invention to produce a low viscosity, lowmole ratio, coatable aqueous dispersion having unique high EAA resincontent.

In the prior art, a high relative proportion of water along with analkali salt as sodium or potassium, for example, is combined with theEAA in an effort to produce a latex, requiring relatively highproportions of ammonia for the reaction, resulting in a highly viscousproduct. With low mole ratios of the salt, say below 0.30 m.r., in aneffort to reduce viscosity, there results substantial untreated,undigested bead material of the 5990 type, whereby the product isvirtually useless. With higher mole ratios, i.e. 0.50 m.r. KOH, athixotropoic solution results like a gel, and being thus unusable, mustbe diluted with water to about 10-15% solids to render the samepourable, whereby the exceedingly high and unwanted water content istherefore present.

The instant invention embraces the discovery that minimal or low amountsof NH₃ as NH₄ OH (or alkali metal salts as KOH) should be provided toloosen up the EAA molecule in forming the dispersion, whereby the lowvolume NH₃ can react fully with the EAA to produce a high reactant yieldbordering on 100%. In this regard, then, much lower ammonia (or sodiumor potassium salts) is employed than in the processes of the Dow patent,whereby the ratio of ammonia to EAA is far lower than contemplated orachieved in the teachings heretofore.

As specially treated herein, the resultant EAA solids product may be ashigh as 95-98% solids as initially reacted, but more commonly on theorder of 45-55%, and with high melting points as compared with theformer prior art low-solids dispersions, whereby the products of theinstant invention may be quickly and effectively dried with less heatinput in view of the high solids level and with no coating or substratedamage. Further, the dispersions of the invention, notwithstanding thehigh-solids character thereof, are of sufficiently low viscosity so asto in no way impede ready application thereof to substrates. Further,especially in the case of Na ionomer, as an applied film, the treatedEAA of the invention has superior engineering properties, as increasedtensile strength, higher melting point, and with minimum or nopinholing. Further, ammonia treatment also results in similar enhancedproperties.

In addition, such unique relative concentration of invention-treatedEAA, by reducing water bulk without loss of desirable applicationproperties, facilitates ease of transportation and utilization innumerous and diverse industrial and commercial coating and and adhesiveprocesses.

Indeed, in producing a high solids EAA dispersion according to thepresent invention, the EAA product resulting from the inventive processcan be sold in the form of beads, powder, flakes, or even gels, treatedin accordance with the invention so as to be nearly "dry" to theindustrial consumer, who then can add such water for dilution as may berequired for specific application purposes, while still achieving lowviscosity 38+% EAA solids content, with manifest advantages in shippingcosts and versatility of usage, or fully ]prepared ab into in dispersionfor sale.

According to the present invention, with respect to production of thetreated EAA suitable for high concentration dispersion, the same can beprepared not only by individual batch processes, and may also be reactedcontinuously and delivered from an extruder, as a screw extruder. Suchform of continuous preparation thereby provides in unique manner anability to have a desired temperature control along the extruder barrellength, and wherein at selected locales therealong at differing stagesof the reaction process, desired additives for reaction, color, filler,etc., may be successivelly introduced into the mix barrel before thefinal treated EAA extrudate emerges from the nozzle.

In this manner, temperature and pressures can be readily controlled in acontinuous production process.

Indeed, with the specially treated EAA extrudate as prepared in anextruder in a substantially continuous basis, the extrudate can besliced into chips or pieces of desired size, thereafter packed, andsubsequently used when necessary by an end user by merely placing thechips into water for a short time, as 15-20 minutes, with appropriateagitation to achieve a desired high-solids dispersion as above noted forcoating or other operations.

Illustrative of that which is currently available are untreated EAA beadproducts of the Dow Chemical Company as aforementioned, identified as"Primacor" Dow 5980 (h.m.w.) and Dow 5990 (l.m.w.) beads. The 5980 beadswhen treated as in the aforesaid Dow patent and placed in dispersion(marketed as a "4893"dispersion) is called "water white" and has an EAAconcentration of 25%, while the 5990 beads so treated result in a milkydispersion of a 35% concentration. These are the best known commerciallyusable dispersion products, and which are below the significantconcentrations attained by the present invention.

Dispersions made with treated EAA beads obtained by practice of theinventive treatment method herein, with both 5980 beads and 5990 beads,have EAA concentrations in excess of 38% which are not heretoforecommercially known or thought capable of being successfully produced.The practice of the present invention not only achieves thesesurprisingly high concentrations, but also may do so with ease ofproduction, ease of treatment modifications, ease of shipping, ease ofhandling, ease of drying and nominal-to-note toxic or environmentalhazard concerns.

The utility of the higher concentrations is especially important in thewide usage of aqueous EAA in diverse coating and adhesive compositions,for example. Thus, with an EAA concentration of 25-35% in ordinarily orpresently prepared aqueous dispersions as noted above, the significant:water base greatly delays drying time of the applied coating andincreases costs thereof, both in slower throughput and in increased andprolonged heat requirements.

While EAA can be dispersed in organic carrier liquids resulting in awhole or partly organic-based coating or adhesive having significantlyshorter drying time requirements than with water, environmentalconsiderations involving organic and volatile vapors increasinglymandate, if feasible, far less pollution-prone water based carriers forcoatings.

Nonetheless, the invention also contemplates the useful incorporation,if desired, of small amounts of organic materials, as isopropyl alcohol(IPA) or N-methyl pyrrilidone (NMP), in low percentages in the initialunique treatment of the EAA beads to facilitate the reaction.

As indicated, prior efforts to produce EAA aqueous dispersions followingbead treatment in a batch reactor with ammonia and water struggle toachieve a barely serviceable and low 25% EAA density concentration,while prior preparation of a 35% EAA density, is in practical termsunusable, as contrasted with dispersions resulting from the specialtreatment of the EAA beads in the present invention, as aforesaid,nothwithstanding the common usage of water (H₂ O) and ammonia (NH₃) inboth the prior art practice and the present unique inventive processes,by virtue of the sharply different methods of treatment.

The product and process of the invention herein are also highly usefulfor inks as well as surface coatings, overall pinhole-free films, andlaminating adhesives, as in film-film, film-foil combinations, forexample.

In all aspects of the invention unwanted organic solvents are avoided,in compliance with increasingly stringent environmental requirements.

DETAILED DESCRIPTION OF THE INVENTION

The essence of the invention is the unique preparation of the EAA beadsso that the same are capable of forming a high-solids aqueous dispersionthat achieves the necessary coating characteristics yet withsufficiently reduced viscosity for ready and facile application, as on aweb fed through a high speed rotary gravure press, for example, and withease of drying without coating damage, as a function of the high-solids,high melting point, substantially less-water character of thedispersion.

The EAA molecule includes ethylene groups which are difficult tosolvate. To this end, a chief feature of the invention resides in thediscovery of means for enhancing access to carboxylic acid receptorsites on the EAA molecule for reaction with ammonia (NH₃) with a viewtoward solvating the ethylene. The resultant polymer product whendispersed in water, results in a dispersion having markedly lowerviscosity at high EAA concentrations, heretofore unsuccessfullyattained, and the necessary and desirable quick-dry characteristics andother practical engineering properties notwithstanding the high-solidsnature thereof.

Heretofore it had not been feasible to provide high-solids EAA aqueousdispersions greater than 35% solids of any practical utility, asabove-noted 5990 ammonia-treated product, as the same is so viscous soas to be virtually incapable of flow or physical application as acoating on a substrate, or with inks, etc., while treated 5980 beadsabove 25% and towards 35% concentration becomes a non-flowing gel. Thereis also the problem of undigested, unreacted polymer in the priortreatment of 5980 beads above 25% solids.

By the inventive treatments herein, however, unique high-solids EAAaqueous dispersions may be provided which are highly serviceable anddesirable, and are also liquid and flowable at such high concentration.As earlier noted, the novel treated EAA pellets or beads therefor may beproduced by either a "batch" process in single charge reactors, or as afurther feature of the invention by a "continuous" process as in largelyconventional extruding equipment, per se, providing special aspects ofreaction and control heretofore unknown. The essential aspects thereofare set forth hereinafter:

(1) Batch Process Technique According to the Invention:

In the preparation of the EAA dispersion according to the invention in abasic batch process thereof, untreated EAA beads as procured from DowChemical or other manufacturers are placed in an airtight vessel in thesubstantial absence of water.

In accordance with the invention, for example, a quantity of 0.25 moleratio aqueous ammonium hydroxide (NH₄ OH) is added to the EAA beads, andthe substances are agitated, as by tumbling until a vacuum develops,wherein the ammonia is fully taken up by and reacted with the EAA beads.

This very low mole ratio ammonia source compares with heretoforeemployed 0.39 mole ratio ammonia to obtain maximum 35% solids with 5990EAA beads, and with even higher 0.79 mole ratio ammonia used with 5980beads to attain as much as 25% solids.

The ammonia is preferably about 26 Å Baume aqueous ammonia. Noexternally provided heat is necessary, and the in-drum reaction betweenthe EAA and the NH₄ OH occurs at ambient temperature. During thetreatment period, which may be for about two hours at room temperature,it appears that the aqueous ammonia is totally absorbed into thediscrete EAA beads. In so doing, a substantial relative vacuum developswithin the airtight vessel as the beads become ammoniated. The beads maypartake of a slight color change.

After a period of time, the vessel is opened and the treated beads, ornow-ammoniated beads, are removed. It is important to observe that uponopening the vessel, there is no smell of ammonia (NH₃) therefrom, whichfollows from the presumed absorption of the NH₄ OH as noted above.

After this reaction, water (H₂ O) is slowly added to the treated beadsin an open vessel to achieve a desired solids level. Illustratively fora level on the order of 39.5% solids, the water is added with agitationor stirring, and at this time external heat may be provided, as by asteam jacket to about 195° F. or so. The reaction product is thenpermitted to cool, with light agitation. As a preferred option, theaddition of the water is in a stepwise fashion, i.e. 1/3 H₂ O, stirring,next third, stirring, the last third, and stirring.

The solids level is tested for the final solids contents desired for thecoating, adhesive, or ink application, and sufficient final water isadmixed as necessary to obtain the desired high solids level, e.g. 38%or more.

The resultant dispersion is then preferably filtered throughincreasingly fine mesh, as 20, 60, and 150 mesh, to remove any possiblyunreacted pellets of EAA and any diverse unwanted fibers or detritus.

Thus, in one instance, at about 150° F., a sample made with h.m.w. beadswas taken and found to be 38% EAA solids Water was added to lower thesolids to 35% at room temperature, and the dispersion had a viscositysufficiently low to permit ready coating onto a substrate, a productheretofore unattainable.

The resultant unique 35% treated h.m.w. solids dispersion producedaccording to the ammonia treatment form of the invention has numerousbeneficial and desirable characteristics, including:

(1) Minimal ammonia gas evolves or is driven off for the treated EAAproduct by virtue of the exceedingly low mole ratio above noted, therebyavoiding the cost and concern of environmentally objectionable excessammonia fumes.

(2) This product contains some 40% additional EAA solids with comparablereduction in water as compared with the hitherto highest available 25%solids dispersion with 5980-type beads, with more effective coating ofsubstrates, yet with no adverse viscosity of production difficulties.

(3) Drying or curing of the 38+% treated solids dispersion madeaccording to the invention is on the order of one-third faster than thevirtually unusable prior "4990" dispersion made from 5990 resin (lowmolecular weight of about 12,000) product noted above, withsignificantly less adverse effect on the substrate and energyconsumption. Further, as indicated, a 35% solids product with the 5980high molecular weight (18,000) resin was heretofore unattainable in anyevent.

It is very important to note that while in the illustrative example thesolids level is at 38% or more, the aqueous dispersion of the inventionherein is eminently usable, with a relatively high melting point and alike molecular weight, which in actual fact contrasts sharply andtotally with the virtually unusable 35% dispersion of the prior arttreated beads, as well as the theoretically usable but in factimpractical 25% prior art dispersion for coating/adhesive and likepurposes.

Alcohol/OH⁻ Modification Process

In view of the relative unacceptability of the prior art EAA productbecause of unacceptable viscosity, long drying time, etc., efforts weremade to enhance the same and lower viscosity of the dispersion by theaddition of means other than water. Thus, in the prior art, isopropylalcohol (IPA) has been added to the completed and reacted dispersionlong after the EAA has been treated to make the same. In this prior artusage, the IPA is primarily to dilute the dispersion and permitsomewhate speedier drying of the same when applied as a coating. Noreaction occurs with the EAA when the IPA is used as a diluent in thismanner.

While reducing viscosity and enhancing drying, such use of the IPAintroduces an unwanted alcohol or like organic volatile to cope withenvironmentally along with the gaseous ammonia noted earlier.

According to the present invention, the treatment of the EAA mayoptionally and preferentially include the introduction of isopropylalcohol (IPA) or NMP, as a source of organic solvating medium introducedin small quantity (i.e. 5% or less) directly to the EAA beads at thetime of initial reaction and before completion therof, and providesdiffering results, namely smaller ultimate EAA particle size, and lowermole ratio requirements for the ammonia, as well as enhancing thereaction. The use of the alcohol or NMP in the present invention, then,is to enhance the reaction treatment, and not as a quick-dry addition tothe dispersion proper effected subsequent to bead treatment.

Further, limited introduction of such an organic additive, as forexample NMP, IPA, Dr propylene glycol, permits the mole ratio of the NH₄OH to drop to as little as 0.25 or even 0.10, while yet resulting in theability to produce as high as a 40.5% solids EAA dispersion with goodviscosity and coating ability.

This contrasts markedly with the teachings of the literature and theaforesaid Dow patent, which achieve only a 25% EAA solids result usingthe 5980 resin reacted with a substantially higher mole ratio ofammonia, such as 0.70 mole ratio or higher. Similarly, the inventiveresults contrast sharply with the 35% solids product of the 5990 resinat the 0.35 or higher mole ratio ammonia source.

The aforesaid relaxation of the EAA bead molecule is unnecessary withammonia, which is capable of entering the bead and reacting with theacid sites therein, but has the advantage as noted of further reducingthe amount of ammonia required. In the case of a caustic reaction aswith NaOH or KOH, rather than ammonia, the use of the solvating additiveis preferred to sufficiently relax the EAA molecule to expose thereceptor sites for reaction. While IPA, NMP, and propylene glycol havebeen specifically mentioned, it would appear that any good solvatingmedium or chemical with solvating properties having an OH⁻ groupeffective to expose the acid receptor sites in the EAA molecule beforereaction would be desirable to permit the reaction with a salt orammonia in accordance with the invention.

(2) Continuous Treatment Process According to the invention:

The present invention includes the capability of practicing the same ona generally continuous basis in contrast to a batch or single lot basis.

Thus a substantially conventional twin screw mixing extruder may beprovided into which substantially dry EAA beads are fed from a Banburyor other blade mixer for treatment. The screw extruder advances, andmasticates the beads between the screw flights as the mass moves towardthe discharge nozzle from which the in-extruder treated EAA issues inrodlike form.

At one or more selected locales along the extruder length, NH₃ isinjected directly into the moving mass to react therewith prior toemergence from the extruder nozzle. The speed of the extruder and thelocale or locales of NH₃ introduction are selected so as to permitcompletion of the reaction prior to exit. In this regard, the extruderbarrel can utilize conventional heating and cooling jackets therearoundwhich are controlled as desired to effect the result.

Ammonia in substantially gaseous form as NH₃ may be introduced directlyinto the extruder and into the EAA polymer which will have trace water,producing a solid material at room temperature which is estimated to besubstantially 100% ammonia salt of EAA polymer with only trace/catalyticamounts of water. This EAA solid can then be dispersed into hot water toobtain a desired concentration suitable for coating at any lower level,but including the higher levels of 40-55% which permits ease of coatingapplication coupled with rapidity of drying of the coating on thesubstrate.

In like manner, isopropyl alcohol and water may be injected directlyalong the treated barrel, the rodlike material emerging from the nozzleat a 40% or higher solids ratio, then being cut or fractured asnecessary and blended with added water to attain the desired solidslevel for coating purposes.

The basic technique to achieve a high EAA concentration according to theinvention is to take the EAA polymer in free acid form, melt andmasticate the same as in a heated extruder, and then incorporate andreact ammonia in gaseous form along with a minimum of water asnecessary. In this manner, the ammonia is trapped in the EAA which issubstantially a solid, after which the reacted product can be easily andquickly converted to a desired dispersion concentration.

This contrasts sharply with prior art techniques of effecting batchfabrication of EAA dispersions with high concentrations of NH₄₀ H andwater in a reactor wherein 25% to 35% concentrations of EAA are the bestpractically obtainable. The excess of NH₄ OH present in the standardprior art dispersions, made as from the aforementioned Dow 5880 and5980, is evident when on drying the EAA coatings made from the prior artprocess to produce the residual film, substantial NH₃ is driven off, andwasted or recovered from the atmosphere at additional cost. By theinstant invention, the use of ammonia is reduced on the order ofone-half, with attendant obvious benefits in all respects.

In the prior art practice, as noted, substantial quantities of water,ammonium hydroxide, and EAA beads are admixed and reacted in a reactorvessel substantially simultaneously. Specifically, to a quantity ofwater in the reactor or other vessel, the ammonium hydroxide and beadsare added, the vessel closed, and appropriate heat and agitationsupplied.

In the invention herein, however, the EAA beads and the ammonia (orsodium as NaOH or potassium as KOH) are admixed with only nominal water,namely only that required to carry the reactant, with no additionalwater. This may be effected as desired, but a preferred and efficientmanner is in an extruder, wherein the location, timing, and temperatureof ingredients, especially the NH₄ OH, can be precisely controlled, andin the absence of additional water. In this regard, the enhancingadditive having an alcohol OH⁻ radical, as IPA, propylene glycol, etc.,for example, when extruder-processed, may be controlled andbarrel-introduced prior to introduction of the principal reactant to theEAA. Alternatively, the beads may be treated with the OH⁻ additivebefore being introduced into the extruder barrel.

ILLUSTRATIVE TEST RESULTS

A series of tests were performed which demonstrate the unique factorsentering into the invention. In each test, a quart bottle was filledwith exactly 300 grams of EAA beads.

Test 1: (Prior Art)

39.3 grams of water were added, and the bottle was agitated at roomtemperature by rolling for 1 week, The agitation is generally comparableto that of a Siena mixer or a ribbon blender.

After one week, and after additional extended periods of time, the waterwas still present, with no significant absorption into the EAA beads.Essentially, water is repelled by the EAA beads under such conditions,as is known in the art.

Test 2:

In this test, 5% by weight IPA alone was added, the IPA beingsubstantially entirely free of any water.

In approximately one half-hour, all liquid (the IPA) was entirelyabsorbed by the beads. The beads were somewhat swollen in size.

Test 3:

In this Test, no free water was provided, and a 0.26 mole ratio of a 25%solution of NaOH along with about 45 grams IPA added at the same time,with similar agitation. No heating was provided.

In this instance, all liquid was absorbed into the beads after one day,and no free water whatever was visible. The beads were somewhat swollenin size.

The resultant material in aqueous dispersion provided an excellentcoating, with very good reflectivity, a harder surface and a highermelting temperature than presently known.

Test 4:

In this test, similar to Test 2, 15% NMP was added, and comparableresults were attained as in Test 2.

Test 5:

In this test, 26 Å Baume aqua ammonia was added to the EAA without anyadditional water. The results were comparable to test 3, including thehighly desirable dispersion and coating qualities and characteristics.

With the beads penetrated and softened by the additive, thereby relaxingthe EAA molecule to expose the acids groups, and with the water absorbedas in Test 2, the ammonia attacks the receptor sites of the EAA moleculeto effect the reaction.

Generally it appears that alkaline materials will achieve this result.Sodium, as in NaOH is effective, as is anhydrous or aqueous ammonia.Potassium as in KOH, would achieve similar results, and other alkalinemetal bases as LiOH, etc. Similarly, other amines are operative.

In the prior art, EAA beads were in an environment of high watercontent, at which time NH₃ was added to effect the desired site reactionin the EAA molecule. With such excess amounts of H₂ O present, theamount of ammonia to overcome the presence of so much water in accessingthe EAA reaction sites is so great that the resultant reactant productwas solid, nearly solid, or so highly viscous so as to be unusable inpractical terms, as the material would utterly incapable of reasonableflow, let alone the low viscosity flow necessary for use in higher speedcoating equipment.

The product of the instant invention, by contrast, provides a highsolids EAA coating material which is suitable for use with high-speedcoating equipment, which results in a substantial savings of time,energy and resulting production costs.

The properties achieved in EAA materials made in accordance with thisinvention are evident in the table of test results below. Overallsuperior coating and physical properties with ease of manufacture of theaqueous dispersion are achieved. Illustratively, substantial increas intensile yield and much lower relative viscosity with ready pourabilityand substantially lower drying times accompany the high solids contentof the dispersions of the invention.

    ______________________________________                                        ILLUSTRATIVE SOLIDS DISPERSIONS                                               MADE BY THE INVENTION                                                                      Sample A .sup.1                                                                       Sample B .sup.2                                                                         Sample C .sup.3                                ______________________________________                                        Ultimate Tensile, PSI                                                                        2160      2812      1848                                       Tensile Yield, PSI                                                                           643       2751      1879                                       Secant Modulus 2% PSI                                                                        2360      2750      1950                                       Elongation, %  558       283       252                                        Surface Tension                                                                              38        37        34                                         (dyne/cm)                                                                     Vicat Softening, C.°                                                                  43        46        50                                         Melting Point, DSC, C.°                                                               77.7      79.1      77.3                                       Hardness, Shore D                                                                            40        49        46                                         ______________________________________                                         Legend:                                                                       .sup.1 34-35% ammonium salt solids dispersion made from "5980" resins,        heretofore unattainable. The ammonia is entirely driven off.                  .sup.2 38% solids ionomer dispersion made from "5980" resins partially        neutralized with .25 mole ratio NaOH, heretofore unattainable. There is a     Na residuum.                                                                  .sup.3 38% solids ionomer dispersion made from "5990" resins and with .25     mole ratio NaOH, heretofore unattainable with this lower molecular weight     polymer.                                                                 

What is claimed is:
 1. A process for the production of a reactedethylene acrylic acid (EAA) product comprising the steps of:providing aquantity of EAA polymer, selecting a reactant from the group consistingof ammonia, ammonium hydroxide, sodium hydroxide, and potassiumhydroxide, adding a quantity of the selected reactant in the range of0.10 to about 0.25 mole ratio to the EAA under dry conditions in anamount sufficient for the selected reactant to swell the EAA polymer toexpose reactor sites of the molecule so that the positive ions of theselected reactant can reach the reactor sites of the EAA moleculesthereby to form the corresponding EAA salts thereat, mixing the selectedreactant and the EAA, thereby permitting the same to react together toform EAA salts as a dry product with no additional water added theretoother than that initially present in the said selected reactant.
 2. Theprocess of claim 1 wherein the reaction takes place in a closed vessel.3. The process of claim 1 further comprising the step of terminating thereaction upon development of a vacuum in the closed vessel.
 4. Theprocess of claim 1 wherein said adding the mixing steps occur at roomtemperature and without the positive addition of external heat.
 5. Theprocess of claim 1 wherein said adding and mixing steps are effected inan extruder, and further comprising the step of extruding the said dryproduct from the extruder.
 6. The process of claim 5 further comprisingthe step of severing the extruded product into discrete pieces.
 7. Theprocess of claim 1 wherein said EAA polymer is in the form of discretebeads.
 8. The process of claim 1 further comprising the step of admixinga solvating bead-swelling medium to the EAA at the said mixing step ofthe selected reactant and the EAA to facilitate ready reaction of theEAA with the selected reactant to form the EAA salts.
 9. The process ofclaim 8 wherein the bead-swelling medium is selected from the groupconsisting of isopropyl alcohol (IPA), n-methyl pyrrilidone (NMP), andpropylene glycol.
 10. The process of claim 8 wherein said adding andmixing steps occur at room temperature and without the positive additionof external heat.
 11. The process of claim 1 further comprising the stepof subsequently admixing the reacted EAA with water to form an aqueousdispersion of the EAA in the water vehicle.
 12. The process of claim 11wherein the proportion of EAA solids in the dispersion is between 35%and 55%.
 13. The process of claim 12 wherein the proportion of EAAsolids in the dispersion is 38% or greater.